Author: Noyafa–CCTV Tester
Question: How does the cable fault tester work? Answer: Cable fault tester The main unit is used to measure the nature of the cable fault, the total length and the approximate position of the cable fault point from the test end. The cable fault spotter is the cable fault tester host to determine the cable problem: How does the cable fault tester work? Answer: The main unit of the cable fault tester is used to measure the fault nature of the cable fault, the total length and the approximate position of the cable fault point from the test end. The cable fault locator is to determine the precise position of the cable fault point on the basis of the cable fault tester host determining the approximate position of the cable fault point.
For buried cables with unknown direction, a path meter is required to determine the underground direction of the cable. The basic method for testing power cable faults is to apply a high-voltage pulse to the faulty power cable to generate a breakdown at the fault point of the cable. When the fault breakdown point of the cable discharges, it generates electromagnetic waves and emits sound at the same time. The working principle of the application of arc reflection method (second pulse method) in cable fault location: first, a high-voltage pulse with a certain voltage level and a certain energy is applied to the faulty cable at the test end of the cable, so that the high-resistance fault point of the cable is hit. through arc.
At the same time, a low-voltage pulse for measurement is added to the test end. When the measurement pulse reaches the high-resistance fault point of the cable, it encounters an arc and reflects on the surface of the arc. Since the high-resistance fault becomes an instantaneous short-circuit fault during arcing, the low-voltage measurement pulse will have obvious impedance characteristic changes, so that the waveform of the flashover measurement becomes the low-voltage pulse short-circuit waveform, making the waveform identification particularly simple and clear. this is what we call“second pulse method”.
The reflected waveform of the received low-voltage pulse is equivalent to the waveform of a complete short circuit of a wire core to ground. The low-voltage pulse waveforms obtained when the high-voltage pulse is released and when the high-voltage pulse is not released are superimposed, and the two waveforms will have a divergence point, which is the reflected waveform point of the fault point. This method combines the low-voltage pulse method with the high-voltage flashover technique, making it easier for testers to determine the location of the fault point.
Compared with the traditional test method, the advanced point of the secondary pulse method is that the complex waveform in the shock high-voltage flashover method is simplified to the simplest low-voltage pulse short-circuit fault waveform, so the interpretation is extremely simple, and the fault distance can be accurately calibrated.
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